Red Rover is not very cold hardy. I had a couple under my polycarbonate roof, attached to my home a few years ago. They had grown well during the summer, they had sent out a vines vines around 20 feet long. That winter, only got down to the mid to high 20s, and they fried totally dead, even what was below soil in the pots.

If your zone 9 proves too cold for the Frederick variety, I would go with Nancy Garrison. I have a apparently seedling stain of it, it takes my cold here, down to the low 20s, with very little damage; produces mostly 2 inch or plus, very flavorful sweet purple fruits.

I have 1,000s of seeds from last seasons fruits, and a few really tiny seedlings, but they are just now trying to decide to live or die after a low of 23F a month or more ago. I know that Monterey Bay Nursery has plant, but they are a whole Sale nursery, find a retail nursery which sell their plants if in the Bay Area, should be no problem finding in SoCal, where do you live? You should be able to find Nancy Garrison and etc vines in a google search for plants, I did in a search last season.